If it is a colorway which is still being produced, check the website of an online Hagen-Renaker dealer or eBay for the current retail price.
If it is a retired colorway or mold, the best place to look is in “Sold” (not “Active” or “Completed”) listings on eBay. Prices for Active or Completed listings may be unreasonably high.
Many Hagen-Renakers are rare or hard-to-find, and seldom come up for sale, making it difficult to find recently sold examples. I have indicated which molds and colorways are “Rare” and “Hard-to-Find [htf]” The value of rare and hard-to-find colorways is generally at least two to three times greater than common colorways.